Add platform_filters support for PBXTargetDependency.

[mangerlahn]

Hi again,

thank you for quickly implementing platform_filters support. While this fixes my usage, I still get a warning when running xcodeproj:

[!] Xcodeproj doesn't know about the following attributes {"platformFilters"=>["macos"]} for the 'PBXTargetDependency' isa

I attempted to fix this myself, feel free to take a look.

[dnkoutso]

@mangerlahn interesting so this exists for PBXTargetDependency as well.

Can you add a CHANGELOG entry as an enhancement please?

[mangerlahn]

Done :)

[dnkoutso]

Seems like lint failed.

Inspecting 123 files
...............C...........................................................................................................

Offenses:

lib/xcodeproj/project/object/target_dependency.rb:32:1: C: Trailing whitespace detected.

123 files inspected, 1 offense detected
Error: Process completed with exit code 1.

You can run bundle exec rubocop -a at the root which should fix it.

[dnkoutso]

thanks!